Circular Pattern - Problem Driving Instance Count with Design Table

[Slagathor]

I have set up a circular pattern about 5 different ways...and none of them work. I am about to rip my hair out...

I am trying to get a design table to drive a generalized bolt pattern sketch, with everything driven by the DT. The one thing that is not configured...is the center point or the pattern. It must remain fixed.

Simple enough..right?

Here is my issue... No matter how I set up the sketch, when the instance count is changed by the DT...the sketch goes undefined.

Then, the NEXT time the DT is changed...then the center starts walking off and the pattern goes haywire. Basically, it appears that SW can not handle updating of instance counts, without dropping dimensions, and then losing constraint.

Attached is an example, with a design table. The sketch for the pattern was made with the following steps.
1. Create horiz construction line, centered on the part.
2. Draw hole to be pattered, dimension the diameter
3. Pattern hole, (4 instances) centered on part
4. At this point, we will have the following dimensions

*Instance Count (I assigned this D1) - created by the pattern feature
*Hole Dia (I assigned D2)
*Radius of the pattern (D3)- created by the pattern feature
*Relative Angle (D4)- created by the pattern feature
*Spacing Angle (D5)- created by the pattern feature

Now..I set up a DT with D1-D5. I can vary the hole size, the radius of the pattern, the angles...all works. D2, D3, D4, D5...can change them all..and everything works as it should.

Now...change D1...the count... to 6. Go back to the part. Everything looks like it worked. But it didn't. Open the pattern sketch. D3, D4 and D5 are GONE!

Now...go back and change D1 back Qty 4 again....bye bye symmetric pattern.

I have tried more sophistated ways to make this work...but nothing will fix this.

When the instance count changes...SW loses relative location...and when that happens...it deletes the dimensions required to keep the sketch fully defined. Then..when you change it again..it goes haywire....

As it stands now...the only thing I can think of is to make series of hole patterns... 4,6,8,10,12,14,16,20,24,30,32,36 ....and switch between them using suppression states depending on how many holes I want...

Sigh... Anyone have a workaround?

 

[CorBlimeyLimey]

Create one hole and create a Circular Pattern of the hole feature and use a DT to control that feature pattern instead of a sketch pattern.

 

[Updraft]

I agree with CBL. Use a feature pattern, not a sketch pattern. Though improvements have been made in sketch patterns in SWX2011 they are still more trouble than they are worth compared to using a feature pattern.

- - -Updraft

 

[Slagathor]

Good tips guys...I will try that....

 

[Slagathor]

Excellent...worked 100%.... I can not believe I did not think of that.